Sandpaper-drum



W. L. BROWNE.

SANDPAPER DRUM.

APPLICATION FILED OCT. 2, 1920.

' Patented Apr. 12, 1921. a? :52

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SANDPALPER-DRUM.

Specification of Letterslatent.

Patented Apr. 12, 1921.

Application filed October 2, 1920. Serial No. 414,172.

To all whom it may concern Be it known that I, WARREN L. BROWNE,

a citizen of the United States, and resident of Vallejo, county ofSolano, State of California, have invented a new and usefulSandpaper-Drum, of which the following is a specification. Y

The present invention relates to improvements in sand papering machinessuch as are used for smoothing, polishing, shaping and grinding wood orother material, and has particular reference to certain improvements .inthe rotary drums for holding and maintaining sheets of sand paper orlike rections. I v means the paper will be prevented from abrasivematerial in proper position for use.

One of the objects of the invention is to provide a sand paper drum uponwhich the sheet of sand paper may be securely and evenly clamped andeasily and quickly adjusted to properly conform to the drum, there beingprovided a novel form of adjustable clamping means for this purpose.

In sand papering machines wherein the paper is clamped upon the drum byclamping devices on the ends and elsewhere on the drtun, when the paperbecomes heated by friction developed in the operation of the drum, saidpaper contracts and often bulges or buckles or even tears or slips outof the clamps, continued use of the drum often causes irregularity to beformed in the paper or causes it to loosen. Under these conditions thedrum does-not provide for a satisfactory abrasive action and usuallycannot be used until the difiiculty is remedied. This amounts tore-clampi ng'and readjusting the paper and requires the expenditureofmuch time and labor.

With my improved drum I eliminate the hereinbefore noted objections byprovision of means for exerting at all times a yielding tension pulledupon the side edges of the sheet of paper while the latter is clampedupon the drum, whereby when the paper contracts or otherwise loosens orbulges the tension means will yield and at the same time pull upon thepaper in opposite di- By this yielding of the tension tearing or bulgingand working loose in the clamps. The tension pulls exerted while thetension means yields will cause the paper to stretch and be smoothed outon the surface of the drum. The force of the tension ull is such thatsaid means will yield beore the paper tears or slips in the clamps butis sufficient to stretch and smooth out the irregularities in the paper.

The invention possesses other advantages and features, some of which,with the fore going, will be set forth at len h in the followingdescription wherein shall outline in full that form of the inventionwhich I have selected for illustration in the drawings accompanying andforming a part of the present specification. In' said drawings I haveshown one form of the construction of my invention but it is to beunderstood that I do not limit myself to such form, since the inventionas expressed in the claims may be embodiedin a plurality of forms.

Referring to the drawings; Figure 1 is a top plan view of the invention;Fig. 2 is a sectional view taken on line 22 of Fig.

5; Fig. 3 is an inside elevation of one, of the clamping devices,showing the drum shaft in section; Fig. 4 is a sectional view taken online 44 of Fig. 5; Fig.- 5 is an enlarged longitudinal sectional view ofthe invention; Fig. 6 is a sectional view taken on line 66 of. Fig. 5;.Fig. 7 is a fragmentary clamp bands.

' In the present embodiment of the inven tion there is provided a drum(1) which is hollow and fixed to a shaft (2) that extends throu h walls(3) interiorly of said drum. The rum has a spiral groove 1) therein toreceive the overlapped edges of a sheet of abrasive material (5) such assand paper.

This sheet is wrapped around the drum spi-' rally with the overlappededges in the groove 7 so as to provide an even surface at that oint-Mounted for-longitudinal movement on,

the shaft (2) so as to be movable toward and away from. the ends of said'drum are clamp-' ing and tension devices (6) and (7) which devices arearranged so as to clamp and-hold the sheet (5) upon the drum. Thesedevices are urged outwardly from the ends of the drum by expansionsprings (8) and (9),

- abut the walls (3) of said drum and the said devices. Thus, thedevices are yieldinglyheld extended by said springs and when the sheet(5) contracts due to the heat produced by'friction when in use, saiddevices yield against the action of the springs and prevent thesheetfrom tearing or slipping in the clamps. The sheet is at all times heldunder tensile strain sufficient to make it com form closely to the drum.

Each of" the devices 6-7 comprises a segmental expansible clamping ring10 surrounding an annular body member 11 which latter has a centralopening 12 loosely receiving the-shaft 2. n annular clamping band 13 ismounted on the ring 10 and has inwardl extending lugs 14 thereon whichlugs sli ably engage the outer edge of the ring 10 so as to facilitatethe mounting and the retention of the band on said ring. The sheet 5 isto be clamped between the ring and band and one of the segments 15 ofthe ring has a groove 16 extending obliquely across its outer face. Thisgroove is adapted to aline with the adjacent end of the drum groove 4whereby the overlapped edge of the sheet provides an even surface atthis'point on the ring. This provides for a tight, even clamping of thesheet.

To provide for maintaining this alinement of the grooves 4 and 16 whenthe devices 7 and 8 are adjusted said devices carry obliquely arrangedbifurcated guide plates 17, in the bifurcations of which plates areslidably mounted pins 18. These pins are carried by the drum interiorlythereof, thus the devices are, given a twisting or spiralmovementcircumferentially while being moved bodily in either direction on theshaft 2. This spiral motion tends to tighten and cause the sheet tobetter conform to the drum.

' The body member 11 has radial slots 19 therein opening in the innerface and 'periphery thereof. These slots slidably re- 1 ceive guide pins20 carried by the segments 15. The slotsand ins are so shaped as topermit endwise withdrawal of the pin and prevent movementof the pins outthrough the open sides of the slots, there being provided angularprojections 21 on the sides of the pins. These projections have screwthreaded openings 22 on their inner ends and said openings receive thethreaded ends 'of bolts 23 which latter project through eccentricallyarranged slots 24in an operating ring 25; The ring 25 is rotatablymounted on the shaft'2 and operates against the inner face of the bodymember 11. A sleeve 26 is mounted on the shaft2 and has an end flange 27which abuts the ring 25. vThe springs surround these sleeves and attheir outer ends abut said flanges. A gear toothed segment 28 is fixedto the ring 25 and meshes similar pinion 31 on the inner end of a shaft.32. The shaft 32 projects through the body member 11 and on its outerend is angularly faced as at 33, for coeperation with a suitable tool,not shown, whereby the shaft 32 is rotated, the worm 29 moves thesegment 28 and rotates the ring 25. When the ring 25 as shown in Fig. 3is rotated from left to right the bolts '23 move toward the outer endsof the eccentric slots 24 and toward the periphery of said ring. Thiscauses the pins 20 to move outwardly in the slots 19 and the ringsegments 15 move correspondingly equally causing the ring 10 to expand.When the ring 10 is expanded the sheet 5 will be clamped between thering and band 13. Reverse movement of, the operating ring 25 causescontraction of the ring 10 and v this will release the sheet 5. Theoutward movement of the devices 6 and 7 bodily is limited by stopcollars 34, and 35 fixed by set screw 36 on the shaft 2 adjacent the endof said shaft. Interposed'between. the device 6 and the stop collar 34is a larger collar 37 which is heldin place by set screws 38. Thiscollar abuts the device 6 and holds the device against outward movementon the shaft 2.

To provide for stretching the abraslve sheet 5 just after it is put onthe drum the device 7 is arranged so that it can be moved outwardly onthe shaft 2 and away from the adjacent end of the drum. This adjustmentis provided for by an annular nut 39 provided with internal screwthreads 40. The nut 39 is mounted upon a flanged externally threadedsleeve 41 fixed to the shaft 2 by set screws 42 which screwsextendthrough the flange 43 of said sleeve for engagement with the shaft. Oneface of the nut bears against the body member 11 of the device 7. v

Operation The sheet 5 of abrasive material is wrapped upon the drumspirally so that the edges lie overlapped in the grooves 4 and 16 withthe side edges of the sheet extending over the expansible-clamp rings 10of the devices 6 and The bands 13 are then slipped over the sheet 5 andin place over the rings 10. The shafts 33 are turned so as to turn I atensile strain. The other s ring 8 yields somewhat since the sheet isclamped in the device 6 and said device is ulled by the stretching ofthe sheet inwar y toward the adjacent end of the drum. This'places anequal strain on the sheet 5 from both sides and both devices areslightly spaced from the ends of the drum. As the sheet is stretched itis also twisted by reason of the oblique or angular guides 17 and as aresult of these two actions the sheet is caused to be wrapped tightlyupon the drum to conform closely thereto and provide an even effectiveabraslve surface entirely around said drum.

As the drum is rotated at high speed when in use, the friction createdby the abrasive action causes the sheet to contract or buckle.Ordinarily where nogive is permitted the sheet will slip from the clampsor tear or otherwise become irregular in contour by bulging or buckling.When this contraction occurs the devices 6 and 7 are pulled toward theends of the drum against the action of v the springs 8 and 9. Thesprings therefore yieldingly exert an equal tension strain from oppositesides of the sheet and prevent the tearing or bulging or slipping ofsaid sheet whereby at all times the sheet is caused to conform closelyto and provide an even abrasive surface upon the drum.

I claim:

1. A device of the character described comprising a drum, a sheet ofabrasive material on said drum, devices at the ends of the drum withinwhich the sheet is clamped and held on the drum, and spring means urgingsaid devices outwardly away from the ends of the drum.,

2. A device of the character described comprising a drum, a sheet ofabrasive material on said drum, devices at the ends of the drum withinwhich the sheet is clamped and held on the drum, and spring means urgingsaid devices outwardly away from the ends of the drum, and means forbodily moving one of the clamping devices relative to the'other.

3. A device of the character described comprising a drum, a sheet ofabrasive material on said drum, devices at the ends of the drum withinwhich the sheet is clamped and held on the drum, and spring means urgingsaid evices outwardly away from the ends of the drum, a shaft supportingsaid drum, a member fixed to the shaft and limiting the outward movementof one of said devices, and a member adjustable upon the shaft andengaged with the other of said devices.

4. A device of the character described comprising a drum, a shaftsupporting the drum, a sheet of abrasive material wrapped upon the drum,devices on the shaft and spaced from the end of the drum for clampingsaid sheet, spring means for urging said devices outwardly, and meansfor adjusting one of said devices longitudinally on the shaft relativeto the other.

5. A device of the character described embodying in its construction, arotary drum, a sheet of abrasive material wrappedaround the drum, anexpansible ring at each end of the drum, means for expanding andcontracting said rings, bands surrounding said rings, said sheet beingclamped between said rings and bands and spring means yieldingly forcingsaid rings outwardly from the ends of the drums.

6. A device of the character described embodying in its construction, arotary drum, a sheet of abrasive material wrapped around the drum, anexpansible rin at each end of the drum, means for expan ing andcontracting said rings, bands surrounding said rings, saidsheet beingclamped between said rings and bands, and spring means yieldinglyforcing said rings outwardly from the ends of the drums, and means formoving springs urging said devices outwardly away from the ends of thedrum, a stop member fixed on said shaft and limiting outward movement ofone of said devices and a stop member adjustably mounted on the shaftand en a the other device.

g-gmg WARREN L. BROWNE.

